Blade balancer



June 13, 1961 A. J. KARRELS BLADE BALANCER Filed March 15, 1957 MAGNET 2 Sheets-Sheet l INVENTO A. J. Karre s June 13, 1961 A. J. KARRELS 2,987,924

BLADE BALANCER Filed March 13, 1957 2 Sheets-Sheet 2 A. c s Fig. 6. BY

United States Patent 2,987,924 4 BLADE BALANCER Alvin J. Karrels, Rte. 1, Port Washington, Wis.

. Filed Mar. 13, 1957, Ser. No. 645,713

2 Claims. (Cl. 73-480) This invention relates to balancing devices such as used for cutter blades of rotary mowers, fan blades, propellers, and other rotatable devices, and in particular an annular magnet positioned to retain a blade or other device on a rotatable conical-shaped spindle wherein the magnet is adjustable in relation to the spindle so that blades having center openings of different sizes may be accurately balanced on the device and wherein blades are mounted in balancing positions without screws, bolts, or other fastening elements.

The purpose of this invention is to provide a balancing device upon which cutter blades, fan blades, propellers, and other devices may readily be positioned and by which the state of balance of substantially any rotatable device having a center opening may be checked.

Various types of wheel and blade balancing devices have been provided, however, in substantially all devices of this type considerable time is required for mounting the device to be balanced upon the balancing machine. With this thought in mind this invention contemplates a balancing machine having a magnet for re taining a blade or the like on a conical-shaped spindle in which the magnet is slidable in relation to the spindle so that a blade or the like may be snugly fitted to the spindle and readily gripped by the magnet thereby obviating the necessity of using mechanical fastening devices, and making it possible to remove and replace a blade as many times as may be desired in a balancing operation.

Cutter blades of rotary mowers are of various lengths, ranging from one to four or more feet, and the center openings of such blades are of various sizes. Such blades operate at relatively high speeds making accurate balance thereof essential to prevent disintegration of the blades and also to prevent excessive wear in the bearings. In balancing such blades it is necessary to remove a blade to grind of]? a portion and replace the blade several times before accurate balance is obtained, and where it is necessary to use wrenches or screw drivers for releasing and tightening bolts and screws the balancing operation consumes considerable time.

The Object of this invention is, therefore, to provide a balancing device for cutter blades, fan blades, propellers and the like in which blades or the like may readily be placed on and also readily removed from the device.

Another object of the invention is to provide holding means for a machine for balancing blades and the like in which blades having center openings of different sizes are readily fitted thereon.

Another important object of the invention is to provide a balancing machine on which objects of various types and designs may be positioned for balancing.

It is yet a further object of the invention to provide a balancing machine for cutter blades, fan blades, propellers and the like in which tracking of ends of the blades is readily ascertained.

A further object of the invention is to provide a balancing machine for cutter blades, fan blades, propellers, and the like in which the machine is permanently assembled and permanently mounted on a wall, stand, or other device, whereby it is always ready for use.

A still further object is to provide a balancing machine for cutter and fan blades and the like in which the blades or the like may be rotated either clockwise, or counterclockwise.

And a still further object is to provide a balancing Patented June 13, 1 961 ice . 2 I machine for cutter blades, fan blades, propellers, an other devices in which the devices are secured in bal ancing positions without screws, bolts, or other mechanical fastening means in which the machine is of a simple and economical construction.

With these and other objects and advantages in view the invention a horizontally disposed shaft, mounting means for the shaft, a spindle having a conical shaped section extended from a cylindrical section rotatably mounted on the shafit, a collar slidably mounted on the cylindrical section of the spindle, and a cylindrical magnet mounted in an annular recess in an extended end of the collar.

Other features and advantages of the invention appear from the following description taken in connection with the drawings, wherein:

FIGURE 1 is a longitudinal section through the balancing machine with a magnet shown in the retracted position, and showing a plurality of blades on the conicalshaped section of the spindle, the blades being shown in dotted lines, and the dotted lines illustrating the positions of blades having center openings of different sizes.

FIGURE 2 is a cross section through the machine taken on line 22 of FIGURE 1, showing the inner portions of the collar and spindle.

FIGURE 3 is a cross section through the machin taken on line 3-3 of FIGURE 1, in which the magnet is shown in elevation and the outer portion of the spindle in section. f

FIGURE 4 is a side elevational view of the balancing machine with the parts as shown in FIGURE 1.

FIGURE 5 is an end elevational view of the machine looking toward the conical-shaped end of the spindle.

FIGURE 6 is an end elevational view showing a typical cutter blade of a rotary mower with sharp edges on both ends and with parts broken away.

While one embodiment of the invention is illustrated in the above-referredto drawings, it is to be understood that they are merely for the purpose of illustration and that various changes in construction may be resorted to in the course of manufacture in order that the invention may be utilized to the best advantages according to circumstances which may arise, without in any manner departing from the spirit and intention of the device, which is to be limited only in accordance with the appended And while there is stated the primary field of utility of the invention, it remains obvious that it may be employed in any other capacity wherein it may be found applicable.

In the accompanying drawings and in the following specification, the same reference characters are used to designate the same parts and elements throughout, and in which the numeral 10 refers to the invention in its entirety, numeral 12 indicating a horizontally disposed shaft mounted in a hub 14 of a base 15, numeral 16 a cylindrical section of a spindle having a conical-shaped outer end 18, numeral 20 a collar slidably mounted on the cylindrical section of the spindle, and numeral 22' a cylindrical magnet mounted in an annular recess 24 in the outer surface and in the extended end of the collar. The magnet, which is of the permanent magnet type, may be of any suitable design and the pole pieces may be provided on the extended edge by suitable means. In the design shown in FIGURE 1, the magnet 22 is provided with a south pole portion 23 and a north pole portion 25, and the magnet is spaced from the extended end by a sleeve 27 of ferrous material. The assembly is mounted on a sleeve 29 haw'ng a flange 31, and the sleeve 29 is positioned in the annular recess 24 of the collar 20. A spacing ring 33 is positioned between the sleeves 27 and 29. The sleeves 27 and 29 are adapted to contact at their outer ends a disc or blade on the conical shaped headof the spindle, the ring 33 being aluminum and being separated from the magnet 22 by a flange 35 extended inwardly from the inner edge of the sleeve 27. The north. pole portion 25 of the magnet 22 rests upon a shoulder 37 of the flange 31 of the sleeve 29. By this means the magnetic force is transferred through the sleeves 27 and 29 to a blade, disc, or the like temporarily held on the conical-shaped head 18 f the spindle 16.

The base 15 may be attached to a wall, stand, or other supporting device and the end of the shaft 12 is secured in-a socket 26 in the hub 14 thereof with a set screw 28. The-shaft is provided with ball bearings 30 and 32 which are retained in spaced relation on the shaft with a spacing sleeve 34 and a set collar 36. The set collar 36 is secured in position on the shaft 12 with a set screw 38 and by this means the ball bearings are retained in spaced relation upon the shaft.

With the ball bearings secured in position upon the shaft the cylindrical section 16 of the spindle is placed over the bearings with the bearing 32 positioned against a shoulder 40 in the spindle and with the spindle retained in position by a snap ring 42 which springs into an annular recess 44 in the section 16 of the spindle.

The collar 20 is slidably mounted on the outer surface ofthe section :16 of the spindle and the outer end of the collar is provided with an annular recess 46 that is positioned to receive an outer shoulder 48 of the spindle as the collar is moved outwardly to position the outer end surface of the magnetized sleeves 27 and 29 against the inner surface of a blade for holding a. blade, such as one of the blades indicated by the dotted lines 50 and 52 on the conical-shaped section of the spindle. By this means the magnet will retain blades or other devices having center openings of different sizes upon the spindle.

The collar 20 is also provided with an inner annular groove 54 in which a friction ring 56, such as a ring made of neoprene, or the like, is positioned, whereby with the ring 56 frictionally engaging the outer surface of the section. 16 of the spindle the sliding travel of the collar on the-spindle is restricted, and by pressing a blade against which the end surface of the magnet is positioned toward the conical-shaped surface of the spindle the blade will be retained in position on the spindle with the center holefitting snugly over the end of the spindle.

Although a rotary cutter blade 58 having cutting edges 60and 62 and a center opening 64 is shown in FIGURE 6 it will be understood that a fan, propeller, or any other device having a center hole may be balanced on the machine.

Operation With the parts assembled as illustrated and described the spindle with the collar 20 and magnet 22 thereon extends outwardly from the base 15 and when it is desired to balance a blade or check the tracking of the ends of blades-or the like, the device to be balanced or checked is positioned with a hole in the center thereof over the conical-shaped section of the spindle, and the magnet and the sleeves 27 and 29 are moved along the spindle until the end. surfaces of the latter are in e c s m nt with the device whereby the magnet holds the device. By this means a device is retained in position on a spindle as it is rotated, and by rotating the device the balance and also the tracking are readily checked.

From the foregoing specification, it will become apparent that the invention disclosed will adequately accomplish the functions for which it has been designed and in an economical manner, and that its simplicity, accuracy, and ease of operation are such as to provide at relatively inexpensive device, considering what it will; accomplish, and that it will find an important place in the art to'which it appertains when once placed on the market.

It isthought that persons skilled in the art to. which the invention relates will be able to obtain a clear understanding of the invention after considering the description in connection with the drawings. Therefore, a more lengthy description is regarded as unnecessary.

Changes in shape, size, and rearrangement of details and parts such as come within the purview of the invention claimed may be resorted to in actual practice, if desired.

Having now described the invention that which is claimed to be new and desired to be procured by Letters Patent is:

1. In a balancing machine, the combination which comprises a shaft, a base for mounting the shaft in a horizontal position, a spindle having a conical-shaped section extended from a cylindrical section, the larger end of the conically shaped section being disposed toward said cylindrically shaped section, means rotatably mounting the spindle on the shaft, said spindle having an annular shoulder extended from its outer surface, a collar mounted at least partially on the base side of said shoulder to slide longitudinally on the cylindrical section of the spindle, said collar having an annular recess positioned to receive the shoulder of the spindle for limiting outward travel of the collar on the spindle, and'magnct means carried by the extended end of the collar and disposed on substantially all sides of said collar for engaging a blade on two opposite sides of said collar regardless of the relative rotational positions of the blade and collar, and holding means mounted in said collar and adapted to engage said cylindrical portion of said spindle to hold said collar in a desired position on said spindle whereby said blade is held in place on said cone by said magnet means.

2. The balancing machine of claim 1 in which said collar holding means is a friction ring.

References Cited in the file of this patent UNITED STATES PATENTS 1,778,481 Boucher Oct. 14,1930 2,201,982 Bazarek May 28, 1940 2,360,982 Beechlyn Oct. 24, 1944 2,518,226 Drake Aug. 8,.1950 2,720,804 Brown Oct. 18, 1955 2,769,642 Berry Nov. 6, 1956 

